1. Field of the Invention
The invention relates to novel systems for the delivery of peracid oxidants for bleaching or cleaning applications, which oxidants may be generated from peracid precursors. More particularly, this invention is concerned with the formation of liquid peracid bleach activator systems in which a peracid precursor may be stably maintained in colloidal dispersion form.
2. Description of the Pertinent Art
Fong et al., U.S. Pat. No. 4,778,618 and Fong et al., U.S. Pat. No. 4,959,187 disclose certain preferred peracid precursors, also known as "activators" or "bleach activators", which have the general formula: ##STR1##
wherein R is, for example, C.sub.1-20 alkyl, .O slashed. represents C.sub.6 H.sub.4 and Y and Z are separately H or another substituent, typically a water-solubilizing group. However, both references state that the depicted granular activators and the hydrogen peroxide source may need to be kept separate to prevent premature decomposition.
Two patents to Sanderson, U.S. Pat. Nos. 4,496,473 and 4,613,452, on the other hand, recite and claim only enol ester activators. The activators are combined with nonionic surfactants to provide acidic aqueous "emulsions" which incorporate hydrogen peroxide. The Sanderson patents recite the use of the depicted enol ester activators exclusively and furthermore relate only to those emulsifiers which have HLB (hydrophile-lipophile balance) values the same as, or at least not differing appreciably from, the corresponding value for the enol ester activator or combination of enol ester activators dispersed in the composition.
Certain other art disclose stable microemulsion systems (Loth et al., U.S. Pat. No. 5,082,584 and Loth et al., U.S. Pat. No. 5,075,026), while others disclose the suspension of certain types of insoluble activators or peracids in liquid systems (Liberati et aL, U.S. Pat. No. 5,073,285; Gray et al, U.S. Pat. No. 5,019,289 and Gray et al., U.S. Pat. No. 4,891,147). Finally, two references suggest the solubilization of particular peracids in essentially non-aqueous (containing less than about 5% water) surfactant solutions (Barnes et al., EP 340,000 and van Buskirk et al., EP 484,095).
However, none of the art teaches, discloses or suggests the use of colloidal dispersions to deliver stable formulations containing surface active peracid precursors, preferably those without ionizable groups.